[PATCH v3] erofs-utils: lib: name worker threads erofs_compress

[Nithurshen <nithurshen.dev@gmail.com>]

Set a specific thread name for the multi-threaded workqueue workers
to make debugging, profiling, and process monitoring significantly
easier.

Previously, worker threads inherited the name of the parent process
(e.g., mkfs.erofs), making it difficult to distinguish them from the
main thread in tools like top, htop, or ps.

This utilizes prctl(PR_SET_NAME) on Linux and pthread_setname_np
on macOS to explicitly label these threads as "erofs_compressor" upon
initialization in the workqueue's .on_start() callback.

Signed-off-by: Nithurshen <nithurshen.dev@gmail.com>
---
 lib/compress.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/lib/compress.c b/lib/compress.c
index 4a0d890..66b3b8b 100644
--- a/lib/compress.c
+++ b/lib/compress.c
@@ -26,6 +26,9 @@
 #include "liberofs_compress.h"
 #include "liberofs_fragments.h"
 #include "liberofs_metabox.h"
+#if defined(__linux__)
+#include <sys/prctl.h>
+#endif
 
 #define Z_EROFS_DESTBUF_SZ	(Z_EROFS_PCLUSTER_MAX_SIZE + EROFS_MAX_BLOCK_SIZE * 2)
 
@@ -1427,6 +1430,12 @@ void *z_erofs_mt_wq_tls_alloc(struct erofs_workqueue *wq, void *ptr)
 {
 	struct erofs_compress_wq_tls *tls;
 
+#if defined(__linux__)
+	prctl(PR_SET_NAME, "erofs_compress");
+#elif defined(__APPLE__)
+	pthread_setname_np("erofs_compress");
+#endif
+
 	tls = calloc(1, sizeof(*tls));
 	if (!tls)
 		return NULL;
-- 
2.51.0